Electric fans of all types have traditionally been an effective way to provide climate control within a living space. During the summer months, electric fans provide a very low cost solution to keep air circulating within a living space, and hence, help keep temperatures from reaching uncomfortable, and sometimes dangerous, levels. In recent years, electric fans have been made increasingly efficient and more powerful through advancements in electric motor technology. Many electric fans today, such as box fans, incorporate four pole and six pole split capacitor motor technology. While this technology increases efficiency and power, it does require relatively higher operating voltages.
While existing electric fan assemblies have all been designed to be safe for their intended use, it is desirable to not only meet, but exceed safety standards set by various organizations, including independent organizations such as Underwriters Laboratories (UL). With this goal in mind, it is desirable to electrically isolate electric motors from other portions of the fan assembly. This is especially true when the fan is being operated in very humid conditions or when the air being moved by the fan has high moisture content. Condensation caused by the air can create a current leakage pathway between the fan motor and other parts of the fan, such as a metallic shroud of a typical box-type fan. In such cases, these other parts of the fan can become electrically charged. Electrical isolation of the fan motor prevents such occurrences.
Naturally, isolation of electrical components is well known. However, presently-known attempts at electrical isolation have many drawbacks. For example, one known insulated box fan employs a plastic isolator ring that is attached to the fan housing at a first set of points and separately attached to the fan motor at a second set of points. The attachments are implemented with screws. One problem associated with this fan is the difficulty in alignment of the attachment points between the isolator ring and the motor. This difficulty is created by the ring being a single component having multiple attachment points. Because all of the attachment points are fixed to a single component, alignment of the attachment points are linked together, thereby creating alignment and tolerance constraints. This creates manufacturing quality concerns. Furthermore, because the isolator ring is a single component, it is more susceptible to manufacturing defects caused by inconsistencies between each of the attachment points, dimensional or otherwise. Another problem is the cost of the components and the assembly. Because of the multiple attachment points, the number of screws needed for the attachment points, the size of the isolator ring, and other factors, the assembly is relatively costly.
In another box fan known in the art, plastic insulating grommets or sleeves are used to electrically isolate a fan motor from the metal housing. The insulating sleeves are mounted in recesses in the motor casing and are configured to receive fasteners which connect the motor to metal motor mounting brackets connected to the metal housing. The insulating sleeves are also effective to electrically isolate the fasteners from the metal brackets.
It is also known in the art to use insulating grommet sleeves to electrically isolate metal motor support brackets from a fan housing. However, this is less desirable because it does not electrically isolate the motor from the metal motor support brackets themselves. Thus, a user could receive an electrical shock by touching the metal motor support brackets should a current leakage situation occur between the motor and the metal support brackets, even though the fan housing is electrically isolated from the motor.
It has been found that new insulating solutions can be more effective to reduce weight, cost, ease of manufacturing, and assembly time than previously known solutions to electrically isolate a motor from a fan housing.